Plastic fabric filter



June 28, 1955 E. F. WEBB ET AL PLASTIC FABRIC FILTER Filed Sept. 30, 1949 W @my mi Mtns-2s PLASTIC rannte FILTER.

Edmond F. Webb, Franklin Village, andi Andre M.

Hansen, Betroit, Mich., assignors to Chrysler Corporation, Highland Park, Mich., a: corporation of Delaware Appiicationeptember 324i, 19491,. Serial No. r118,872

l Claim. (Cl. 21m- 1691) Ourinvention relates to filters and to the method' of making the same.

More particularly our invention relates toan improved type of liquid filter especially adaptedv for filtering the. gasoline in a motor vehicle fuel tank.

A principal object of our invention is to provide animproved filter for substantially removing all foreign matter from liquid passing'through thefilter.

Another object of our inventionI is` to provide a new and novel type of filter which is particularly adapted to separate gasoline from a mixture of gasoline and water.

A further object of our invention is to provide ani. improved filter which may have its porosity conveniently and accurately predetermined in accordance with the rate of filtering desired and size of particles to. be sepa-Y rated from a fiuid.

AnotherA object of our invention is ton provide anv im proved filter which is capable= ot a selficleaning action during its normal operation.

Still a furtherobject of ourl inventionis to provide a4 new and novel method of constructing our improved filter.

Anotherobject of our invention is to-provideeV a; plu rality of layers of resinous fabric materiali in a= filter'of this kind which are securely held together withthef-Warp and woof of respective layers in aselectedl' orientation; by spaced integrally fused bonds of thelmaterial of the fabric.

Other objects andadvantages willbecome more apparent from the following description of' one: embodiment oi" our invention, reference beingy had tothe accompany-- ing drawings ina-Which:

Fig. l is a side elevational view of amotorvehicle fuel tank having a portion brokenaway' tomore-clearly shows the invention.

Fig1 2 is aplan view of`our improvedflter member;

Fig. 3 is a transverse sectionalview taken-on the-.linea 3 3 of Fig. 2.

Fig. 4 isran elevational view partly in section-.illustrating a process for bonding together the resinous fabric layers of the improved filter-member.

Fig. 5'is a fragmentary, enlargedview of thetfilament const-ructionof theplastie cloth utilized inA` ourinvention.

Fig. 6 is a fragmentary enlarged view, similartwFig; 5lshowing` theplastic clothH after ithas been pressed'to-predetermine its porosity.

Fig. 7V is a sectional v-iew taken ontheline 'le-710i? Eig: 1.

In the drawings there is shown aconvent-ional fuelE tank l() which is generally mounted at theA rear'endl'off the motor vehicle but is shown unmounted in the drawings for the purpose of simplicity. The fueltankA 102 is provided: with anL outlet. tube 1l for conveying-'therfuiciI fuel from the tank under the action: of` a conventional; vehiclevv fuel pump. TheA outlet tube IllV is provided; at.. its` innermost endl with a, filterY holder or.k casing, 12.. and: is, supportati: by a. small bracket-` l'S. mounted. on., the

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floor of the tank. The filter casing 12 comprises an inverted sheet metal' cup 40 having a sleeve 41 adjacent the inner surface of its peripheral wall. Disposed over the openV end ofA the casing 12 is a filter member, generally designated byl the numeral I4, which is seated upon the outer end of the sleeve 41. The marginal side wall portions 4Z of'the casing 12 are crimped over the perimeter of the filter member soas to sealingly clamp the edge portions of' the filter member between the sleeve 4I and the edge portions 42 ofthe casing.

The filter'member 14 is madeof sheets of plastic cloth or fabric moldedV together atpredetermined points. There is shown in the drawings, having reference moreI particularlyA to Fig. 3, three layers or plies 1-8, 19 and 20 of plastic cloth, the outer edge portions thereof being fused' together in a circular pattern at the location designated 'byl the numeral I5 in order to rigidity the filter member structure at the locations where it is clampingly en-- gaged between the end of the sleeve 4landthe crimped margin 42' of the casing 12. This fused-l ring also serves to fix the' layersV of' plasticy fiber together. Similarly, as shown in Fig. 2, the three plies of plastic cloth are fused together at locations 16 and 17, the former approximating the center' ot" the plies, the latter locations 17 forming small dotsdispersed generally around the center location- 16. It may be readily seen that the layers orplies off' the-plasticA elothv must be bonded together to prevent separation of` the plies to assure maximum and@ uniformly consistenti filtering action. v

lthouglr variousf typesY of' plastic materialsl may be"- used tcv formA our improved plastic filter, the following synthetic resinous materials have been found very satis;- actory: vinyl chloride and/ or vinylidene chloride, vinyl clrl'oride aceta-te polyethylene andV polytetrafiuoroethylL ene: The filter may be constructed of' multi-layers ot" fabric woven` from filaments extruded froml the foregoing plastic and: other plastic materials. The filaments-f of plastic material are generally circular in cross-section when the-plies are made. I-lcrwever, due tothev pliability.v oplastic material and its: ability, to` take a permanenti set after being subjected. to heat and pressure, the` plies may be press: polished; hot rolledk orv calendered' either before-on after they are= assembled toreduce the porosity thereof? to a predetermined value; Although this step is. not' shownV in: the drawings, any conventional method may beA used to exertl pressure on the filaments tov spread them. outifinlthe planeA ofthe fabric and. to `thereby increaseI theirA eiecti'ye. filteringv capacity; Eig; 5 is a'y magnified; view of. a, plastic plyfsuch: as. 18,' 19.' or 20 having vertical;

" threads. on filaments lli@ and horizontal threadsy or: fila rn'nntsllll: withlopening1021between1 them. Eig. 5 represents the filaments as originally woven whereas Eig., 6:- represents the'ilaments after they.Y have been pressedf by hott rolling;A hotipressing; .calenderingf or some other simi larsprocess; The sizeof' the: opening 162', as shownin. Fig; 6;, may heavariedt in: accordance with the filter re: quirementsdesired., It may bev seen'rthat' theietective fifa? mentzdimensonsi will. vanyin accordance with theapplh cationz. for which the filter; member. is: designed: Eon fleringdirttand Water from gasoline, the: followingzf'abric; construction.liaszbeenafundj satisfactory:

As. previouslyA mentioned; in this specification;vr thev fila mentslflt),lv llllfwhichfarefwovento provide the-.filterY plies 18 19,5.r 2f). are: eachformed; from,v plastic material: byan:l extrusion`v process. From aconsideration of; Figs. 5 and'- 6, which, are. enlarged. magnified, views cfa. fragmentary portion of one of the filter plies, it will be noted that the exterior surfaces of these filter ply filaments 100, 101 and 100', 101 are perfectly smooth. That is, they are not grooved orribbed as would be the case if these individual filaments were formed by twisting together a plurality of separate filament strands. Due to the filaments 100, 101 and 100', 101' being perfectly smooth along their exterior surfaces there is no possibility of leakage of the filterable fluid through the filter ply by passage of the fluid through grooved depressions or channels formed on the filament exterior surfaces. Due to the plastic type of material used for the filaments, there is no fluid absorption by the filaments and thus all uid passing through a filter formed in accordance with this invention passes through the relatively small openings 102 between the several filaments 100', 101'.

While it has been known that mono-filaments are stiffer than filaments formed by twisting together several thin filament strands, still, this does not present a problem in the construction of this particular filter cloth for it will be noted from Figs. 5 and 6, and from the description relating thereto, that the extruded filaments 100, 101 are woven so that the openings 102 (see Fig. '5) are initially larger than the final relatively small size openings 102 (see Fig. 6). However, after weaving of the filter ply from the single strand, smooth surfaced filaments 100, 101 as shown in Fig. 5, then the filter ply is rolled or pressed so as to deform the filaments 100, 101 to the flattened final form shown in Fig. 6. As a result of the method of fabrication of this filter ply, single strand, smooth surfaced filaments may be used to readily form a filter that will only permit fluid to pass therethrough by penetration of the openings between the filter strands, and will prevent uid penetration through or lengthwise of the filaments.

In constructing the filter member 14, the fabric is first pressed as heretofore set forth to predetermine the size of the opening between the filaments and then three plies of the fabric, such as 18, 19 and 20 are piled one on top of the other, the warp direction of the center ply 19 being turned approximately 90 from the Warp direction of the outside plies 18 and 20. The angle which the center ply is turned may vary with the type of filter action required by the filter member 14 and more than three plies may be used if the nature of the uid to be filtered necessitates it. It should be noted, of course, that only two plies of the plastic cloth may be used, one warp direction being turned relative to the other, without departing from the scope of our invention. Similarly, a single ply of plastic fabric may be utilized as a filter by pressing the filaments of the fabric until the fabric has obtained a desired porosity and by fusing the filaments together at predetermined locations to form a sealing surface on the ply for cooperation with the filter holder.

In Fig. 4, of the drawing, is illustrated a dielectric process for simultaneously fusing together the marginal portions 15 of the plastic fabric ply as well as the areas 16 and 17 thereof. This is accomplished by placing the plies of plastic material between two dielectric sealing platters 21 and 22 and fusing them together preferably under pressure by dielectric heating as shown in Fig. 4, it being understood that the platter 21 is brought into engagement with the upper ply of the stack. A typical design of the apparatus used for performing the dielectric heating is shown in Fig. 4 wherein 23 indicates an electronic oscillator connected by wires 24 and 25 to the platters 21 and 22, respectively. The platter 21 is provided with an integral ring portion 26 which cooperates with a ring portion 27 on the platter 22 to form the fused ring at the location 15 on the filter member 14. The platter 21 is also provided with a cylindrical projet. tion 28 which cooperates with a cylindrical projection 29 on the platter 22 for providing the fused dot at the location 16 on the filter. Similarly, the platter 21 is provided with a plurality of projections 30 which cooperate with projections 31 on the platter 22 by forming the fused dots indicated at 17 on the filter member 14. It may be readily seen that once the dielectric heating is finished, the three plies of plastic cloth will be fused together as more clearly shown in Fig. 3. The operating values of the oscillator 23 may be varied in accordance with desired results but at frequency of 17 megacycles at 1400 volts at a time of 36 seconds has been found to be very satisfactory in the making of a filter for use in a gasoline tank. By employing dielectric heating in fusing together the plies and forming the fused ring 15, it is not necessary to rely upon conduction or convection of heat from the exterior to the interior of the assembly for dielectric heating uniformly simultaneously and directly all the selected portions of the assembly throughout its thickness. It is therefore not necessary to apply excessive heat on the outer plies in order to heat the inner plies at the selected locations.

The plastic fabric formed of a plurality of plies of plastic cloth as herein disclosed may be of any desired shape and if desired, the plastic material on the outside of the fused ring at 15 may be trimmed from the filter member 14. It should be noted, however, that a circular ring as at 15 has been shown herein for illustrative purposes only and any fused design may be used without departing from the scope of this invention.

It has been found that this improved filter is noncatalytic to gum forming gasolines. The materials proposed are resistant to the action of aromatic fuels and the aliphatics, methyl and ethyl alcohol, and any other chemical compounds and solvents with which gasoline may ordinarily be found to be contaminated. This filter will successfully remove dirt or foreign particles of any size as well as thread, lint or other filaments commonly found in fuel systems and it will also separate gasoline from a mixture of gasoline and water.

By using the method of bonding as herein disclosed,

the porosity of only a small portion of the filter is affected.

Due to the exibility of the filter member 14, it is selfcleaning because when the surface becomes clogged with dust, mud, or other deposit, the differential pressure across the filter will increase and the filter member will flex due to the suction of the pump. The foreign material will be dislodged and prevent the formation of an obstructing caked deposit on the filter member.

The filaments or threads from which the plastic fabric is woven may comprise thermosetting resins such as phenol formaldehyde resin, urea formaldehyde resin, and other thermosetting compounds. In this case, however, it is preferable to weave the fabric while the plastic filaments are in semi-cured state and fuse the plies together at the areas indicated at 15, 16 and 17 in the foregoing manner by dielectric heat and pressure. The remaining portions of the plies may remain in their semi-cured state or may be finally cured subsequently in an oven.

Although dielectric heating is the only method shown andy described, it should be borne in mind that other methods such as sewing, clipping, stapling, or clamping may be used to maintain the plies of fabric in an assembled relationship without departing from the spirit of our invention.

While we have illustrated and described but one embodiment of our invention, it is to be understood that such is for the purpose of illustration only, and it is contemplated that those skilled in the art may modify certain details without departing'from the scope of the invention as defined in the claims appended hereto.

We claim:

A filter element adapted to be mounted in an encircling support comprising a plurality of superimposed plastic plies woven from extruded filaments of synthetic resinous material, each ply comprising interwoven warp and fill openings between the threads and subsequently compressed and spread out throughout their lengths to provide relatively small filtering openings between the threads suitable for the separation of liquids of differing physical properties, said plies having the warp direction of one ply at an angle to the warp direction of an adjacent ply with said superimposed plies being adhered together at the center of their lter area and at a plurality of other points located at spaced intervals throughout the filter area of the element.

References Cited in the file of this patent UNITED STATES PATENTS 789,062 Prescott May 2, 1905 1,062,532 Blair May 20, 1913 2,297,729 Thomas Oct. 6, 1942 6 Harz et al. July 20, 1943 Strauss Nov. 2, 1943 Strickland et al Aug. 1, 1944 Rugeley Aug. 15, 1944 Behlen July 8, 1947 Oestricker Aug. 12, 1947 Lange Sept. 12, 1950 Smith May 1, 1951 Hersberger June 12, 1951 FOREIGN PATENTS Sweden Feb. 3, 1915 Germany June 15, 1920 Great Britain Dec. 7, 1937 Great Britain Aug. 26, 1938 

